Credit Suisse upgrades Cubist Pharmaceuticals (CBST) to Outperform from Neutral following yesterday's announcement that the company is buying both Optimer Pharmaceuticals (OPTR) and Trius Therapeutics (TSRX).

CBST investors got a look at Dificid sales for Q2 courtesy of early numbers from OPTR Tuesday evening. Q2 sales of the antibacterial drug were $19M, up 13% from a disappointing $16.8M in Q1.

Ultimately, CBST sees Dificid and Trius' tedizolid bringing in a combined $600M to $1B per year, the company said on a CC convened to discuss the deals. (previous)

With the deal for Optimer (OPTR), Cubist (CBST) gets the antibacterial drug Dificid, which it has co-promoted with OPTR since 2011. CEO Michael Bonney notes that the co-promotion experience combined with CBST's "outstanding hospital-based commercial infrastructure," should allow for the maximization of the drug's potential.

Previously, some worried disappointing Q1 Dificid sales ($16.8M versus estimates of ~$20M) would make OPTR less attractive as a takeout target.

Shares of Optimer Pharmaceutical (OPTR+14%) ramped up into the close on reports that AstraZeneca (AZN), Astellas Pharma (ALPMY.PK) and Cubist Pharmaceuticals (CBST) are among the first round bidders for the antibiotic manufacturer. OPTR disclosed almost three months ago that they were working with Centerview Partners and JPMorgan to explore its strategic options, including a potential sale.

The sell-off in Optimer Pharmaceuticals (OPTR-16.6%) accelerates as the session drags on, with losses now well into the double-digits. On top of Needham's downgrade (disappointing Dificid sales may equate to less value for anyone planning an acquisition), Baird chimes in as well, cutting the shares to Neutral from Outperform (price target still $16). (earnings, CC)

More on Optimer's (OPTR-8.2%) Q1 results: Dificid net sales of $16.8M versus $14.4M in Q1 2012. The company sees a 5% increase in demand for the product but Needham's Alan Carr notes that consensus estimates were for Dificid sales of $20M and worries that the "concerning" sales trajectory (0% growth Q/Q) could reduce the premium any potential suitor might be willing to pay to acquire the company. (PR)